title: Effects of dietary glycemic index on brain regions related to reward and craving in men.
abstract: BACKGROUND
  Qualitative aspects of diet influence eating behavior, but the physiologic mechanisms for these calorie-independent effects remain speculative.
  
  
  OBJECTIVE
  We examined effects of the glycemic index (GI) on brain activity in the late postprandial period after a typical intermeal interval.
  
  
  METHODS
  With the use of a randomized, blinded, crossover design, 12 overweight or obese men aged 18-35 y consumed high- and low-GI meals controlled for calories, macronutrients, and palatability on 2 occasions. The primary outcome was cerebral blood flow as a measure of resting brain activity, which was assessed by using arterial spin-labeling functional magnetic resonance imaging 4 h after test meals. We hypothesized that brain activity would be greater after the high-GI meal in prespecified regions involved in eating behavior, reward, and craving.
  
  
  RESULTS
  Incremental venous plasma glucose (2-h area under the curve) was 2.4-fold greater after the high- than the low-GI meal (P = 0.0001). Plasma glucose was lower (mean ± SE: 4.7 ± 0.14 compared with 5.3 ± 0.16 mmol/L; P = 0.005) and reported hunger was greater (P = 0.04) 4 h after the high- than the low-GI meal. At this time, the high-GI meal elicited greater brain activity centered in the right nucleus accumbens (a prespecified area; P = 0.0006 with adjustment for multiple comparisons) that spread to other areas of the right striatum and to the olfactory area.
  
  
  CONCLUSIONS
  Compared with an isocaloric low-GI meal, a high-GI meal decreased plasma glucose, increased hunger, and selectively stimulated brain regions associated with reward and craving in the late postprandial period, which is a time with special significance to eating behavior at the next meal. This trial was registered at clinicaltrials.gov as NCT01064778.
authors.affiliation: New Balance Foundation Obesity Prevention Center, Boston Children's Hospital, Boston, MA, and Harvard Medical School, Boston, MA.
authors.forename: Belinda S
authors.initials: BS
authors.lastname: Lennerz
authors.forename: David C
authors.initials: DC
authors.lastname: Alsop
authors.forename: Laura M
authors.initials: LM
authors.lastname: Holsen
authors.forename: Emily
authors.initials: E
authors.lastname: Stern
authors.forename: Rafael
authors.initials: R
authors.lastname: Rojas
authors.forename: Cara B
authors.initials: CB
authors.lastname: Ebbeling
authors.forename: Jill M
authors.initials: JM
authors.lastname: Goldstein
authors.forename: David S
authors.initials: DS
authors.lastname: Ludwig
mesh_terms: D000328:Adult; D001066:Appetite / Q000502:physiology*; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D001921:Brain / Q000098:blood supply / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D038321:Glycemic Index; D006801:Humans; D006815:Hunger; D008297:Male; D009765:Obesity / Q000097:blood / Q000503:physiopathology* / Q000523:psychology; D019518:Postprandial Period; D012039:Regional Blood Flow; D012201:Reward; D055815:Young Adult
chemical_list: D001786:Blood Glucose